Conversion Of Flavone To Isoflavone: A. Effects. Alyce Ruhoff and Erin Speetzen Ph. D.

Transcription

1 Conversion Of Flavone To Isoflavone: A Computational ti Study on Substituent t Effects Alyce Ruhoff and Erin Speetzen Ph. D. University of Wisconsin Stevens Point

2 Background: What are Flavonoids? Flavanoids are a common polyphenolic compound that are found in plants. The backbone structure is shown below. The consumption of these compounds have been known to have health benefits. These benefits include: Anti-inflammatory Anti-allergic Anti-viral Decreased risk of Certain types of cancer Cardiovascular disease Neurological impairments (Parkinson s s, Alzheimers)

3 Background: What are Flavonoids? Continued. Flavonoids can form different classes. These classes are determined by the oxidation of the ring C of the backbone structure. Each class has different health benefits. Our interest is the formation of isoflavone. This is the only class has been known to penetrate breast and prostate tissue and it has been indicated to possibly be chemopreventive against these types of cancers. B 4' A C 2 3 Flavonoid Skeleton Isoflavone Flavonol Flavone Flavanone Flavanols

4 Kawaga et al. Results It was found that in cytochrome P450 (CYP 450) flavanone was able to convert into flavones, flavanonols and isoflavone when the R group was CH 3. However, when the R group was OCH 3, CYP 450 did not covert flavanone into isoflavone. It is of interest to know how and why substituents have effects on CYP 450 that allows or inhibits the conversion to isoflavone. Xenobiotica 2004; 34:

5 Background: The Mechanism Above is the proposed mechanism based on results from Kawaga et al. Our interest is in the mechanism behind the phenyl shift that converts a flavone into an isoflavone. Xenobiotica 2004; 34:

6 Background: Phenyl Shift 1, 2 phenyl shifts, rearrangements, occur when a phenyl group moves from one carbon to the neighboring carbon These shifts require a driving force. Meaning the new rearrangement forms a more stable intermediate. The phenyl shift in flavones form the isoflavones. The enol form of the isoflavones creates a conjugated system of the two aromatic rings. The conjugated enol form is the more stable form.

7 Method Structures of the enols and ketos form of the flavonne and isoflavone were constructed. Different substituents were added to the para position of the phenyl group, to examine the effect substituents have on the Gibbs free energy of this process. These structures were previously optimize using UB3LYP. However, we wanted to investigate how consistent our results were upon changing the density functional. Our new results use the MO6-2X/6-311+G** level of theory.

8 Results 6 ΔG between Product and Reactant OH OCH3 CH3 H Cl CN NO2 Pketo-Rketo Penol - Rketo Calculations of the Rketo form with substituents CH 3 and CN have yet to be Calculations of the Rketo form with substituents CH 3 and CN have yet to be completed. Contrary to previous results, these results do not follow any trend.

9 Results Continued The spin densities in the list below show the relative electron density for atoms 1 through 31. Any lone electrons will have a density of one. In this case the radical should be on atom 11. However, in the enol form of the product the spin densities show that the electron density is being shared with atom 11 and atom 27. This is not observed in the keto form of the product. Thus the enol delocalizes the radical in an allylic fashion The spin densities and above structure have CH 3 as the substituent group. The trend holds for all substituent groups.

10 Summary of the Project It has been of interest to understand how cytochrome P450 can convert flavones into isoflavones. Therefore the understanding on the mechanism is key. The use of computational method allows for the study the energies of the reactants and the products. Through this process a transition state could be obtained. Additi f b tit t ld h h fl t Th Addition of substituents could change how flavones convert. Thus this study includes seven type of substituents in the fourth position: CH 3, Cl, CN, H, NO 2, OCH 3 and OH.

11 Future Work: Comparing Results The results the we obtained using M06-2X did not yield any trend. Finishing calculations on the reactant keto structures will complete the data. We can then officially determine if a trend does not exist. The new results differ significantly from the previous results The new results differ significantly from the previous results. Higher level calculations must be performed to determine the accuracy of both methods.

12 Future Work: Tautomers The keto group in flavones and isoflavones can form enols. Likewise the enols can revert back to keto groups. In this case the rearrangement is water assisted. After the method and basis set is determined, water will be inserted into all structures. res The water assisted intermediate will then be determined.

13 Future Work: An Enzyme Look Docking studies of the molecules into the enzyme will also be performed. This will help determine if substituents play a role in the way the molecule docks into the enzyme. Depending on how the molecule docks will determine how the phenyl shift occurs.

14 Acknowledgements I will like the thank the following people for their previous work on the project: Michael Wallerich Matt Busta I will also like to thank MU3c for computer time.